As public safety agencies evaluate their two-way radio needs for the future, many are reaching some similar conclusions: radio spectrum is becoming more congested and regulators are requiring public safety to do more with less, the demand for data transmission is more pronounced and often unachievable in narrow-band systems, systems need increased functionality, secure communication is a growing necessity, and improved digital voice quality is essential over more of the coverage area.
It will be appreciated that upgrading a communications network is a major undertaking in terms of time, energy and expense. A number of possible solutions are available, including the digital technologies that are now available.
The Association of Public-Safety Communications Officials (APCO) Project 25 (P25) is an industry-wide effort to set the recommended voluntary standards of uniform digital two-way radio technology for public safety organizations. For a copy of the APCO Project 25 Statement of Requirements, see http://www.apcointl.org/frequency/project25/documents/SOR-2008.pdf. Key objectives include providing enhanced functionality with equipment and capabilities focused on public safety needs, improving spectrum efficiency, ensuring competition among multiple vendors through Open Systems Architecture, and allowing effective, efficient, and reliable intra-agency and inter-agency communications.
One important aspect to any wireless communication standard is providing a mechanism for signaling control information to both receiving and transmitting radios. Within the APCO Project 25 standard, for example, control signaling controls such aspects as Caller Identification (ID) display on receiving radios, confirmation of the ability to transmit by the transmitting radio, and the ability for the Fixed Network Equipment (FNE) to determine the current transmitting radio on the channel.
Accordingly, it is desirable to accurately detect inbound control information. Further, there is a need for a reliable method for accurately determining when a transmitting radio is receiving outbound control signaling and also for accurately signaling caller ID and transmitter control information to the transmitting radios within a wireless communication system.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.